NEW YORK, April 8 (Reuters) - Jamie Dimon, chief executive officer of JPMorgan Chase & Co, the biggest U.S.-based bank, defended the size and business model of his company, which has been criticized as being too big and complicated.

Dimon, in a letter to shareholders with the company's new annual report on Wednesday, said the company is "not a conglomerate" and is "not necessarily" more risky because of its size. The bank is facing tougher capital requirements from regulators than its rivals and has seen analysts ask whether it...